Underreaming apparatus



July 26, 1932. B. GRANVILLE UNDERREAMING APPARATUS Original Filed July 2l, 1925 3 Sheets-Sheet l gunna/woz July 26, 1932. B. GRANVILLE UNDERREAMING APPARATUS original Filed July 21,'1925 :5l Shams-shamk 2 Alle ,Am A

lH1135? 25, 1932- BGRANVILLE 1,868,762

UNDERREAMING APPARATUS Original Filed July 2l, y1923 3 Sheetsheet 3 L30 v gemme/#Won Patented July 26, 1932 .y UNITED STATES PATENT OFFICE BERNARD GRANVILLE, OF NEW YORK, N. Y., ASSIGNOR TO GRANVILLE HOLDING COR- PORATION, A CORPORATION F NEW 'YORKy UNDERREAMING APPARATUS Application led July 21, 1923, Serial No. 652,906. Renewed October 13, 1931.

oil Well, or other vdeep vertical hole.

An object of the invention is to provide indicating means by Which the vvidth' of the I cavity being formed by the underreamer may be known at the top of thevvell as the cavity is in process of being formed. A further Objectis to `provide an under-reamer 'which is self-centering. A still further object is toprovide improved means for feed -ing the under-reamer during the cutting. Other objects and advantages of the invention are hereinafter described.

An under-reaming apparatus of approved construction embodying the invention includes an under-reamer having a cylindri cal body, three arms pivotally mounted on tliebody at angles of 12()o from each other, cutters pivoted to the outer ends ofthe arms, and a plunger in the body adapted to force the arms outwardly When hydraulic pressure is applied to it. `A hollow drillrod is n provided lfor rotating the underfreamer and conducting Water or other` fluid from a force pump atthe top ofthe Wellvto oneside of the plungerof the under-reamer. 4.The plunger is provided With l'a leakagel opening Whose size is dependent upon the extent to which the arms are spread out. The Width of the cavity formed by the under-reamer may, therefore, be determined by the rate of escape of liquid forced against the plunger. This rate may be determined by the pressure in the drill `rod indicated on a vpressure gage atthe top Vof the Well. The diameter of the cavity formedis thus indicated at the top of the Well during the operation of the underreamer. The under-rea1ner and the drill rod are suspended from a hydraulic lift which provides means for gradually -feeding vthe i having a long depending arm 17a and a short arm 18a extending inwardly across the body under-reamerup and down during the. cuttin Y Y v {i} Orderthat the invention may clearly be understood# will describe in detail the specific embodiment of it which is shown in the accompanying drawings, in which Fig. 1 is a diagrammatic sectional elevawhich is suspended from the lift, showing, i

in axial section,.the apparatus for rotating the stem.; I

Fig. 4 isan a-Xial section of the underreamer on the line 4-4 of Fig. 9, with parts omitted forV the sake of clearness;

Fig. 5 `is a similar section on the line 5-5- Fig. 6 is a similar section on the line 6%-6 A y Fig. 7 is a front elevation of one of the i cutters andthe lever on which it is piv-f of Fig. 9;

oted;

Fig. 8 is an enlarged transverse-section-of' the under-reamer on the line 8-8 ofFig.V 6; Fig. 9 is a` similar section on the line 9-9 of Figs. 4 to 6i; y

Fig. 10 is a transverse section ofthe cutters taken onV the line 10-10 of Figs. 4 to 6;

Fig. 12 is a transverse section on the line and Y i v, Y

Fig. 13 is a transverse section ontheline 13-13 of Fig. l1, on the same scale as F1g. 12. The,.underreanier 10, best shown in Figs.

` 12-12 of Fig. 11 onga still larger scale; i'

4 to 13has a cylindrical body 11 in the of the slot 14a!l is a transverse'pivot rod 15aV on Which is pivo-ted a bell crank lever 16a of the under-reamer. In the slots 146 and 140 are similar transverse pivots 15b, 150 on In the loWerpart of the body 11 i which similar bell crank levers 1Gb, 160` are pivoted. vThe pivot rods 15a, 15b, 150 are at different levels so that the short arms 18a,

Fig. 11 is an enlarged side elevationof .75

one of the cutters' partly in section;

186, 18C of the three bell crank levers may extend across the axis of the body without interfering with each other. Space for these arms may be provided in the lower part of the body by extending the slots 14a, 146, 14C inwardly, or, as shown in the drawings, the lower part of the body may contain a cen tral bore 19 having internal longitudinal grooves 20a, 206, 20c opposite the slots 14a, 146, 140 respectively, and providing space for the inner ends of the arms 18a, 186, 180.

The depending arms 17a, 176, 170 of the three bell crank levers are of the same length and the lower part 21 of each of them is U-shaped in Cross-section so as to provide a recess 22 in its outer side. Cutters 23a, 236, 23o are pivotally secured to the lower ends of the arms 17a, 176, 170 respectively. The cutter 23a has a central shaft 24 on which toothed cutting discs 25 separated by spacers 26 are rotatably mounted. The shaft 24 is fixed in a block 27 which is pivotally mounted on a pivot 28a at the lower end of the arm 17a. The pivot 28a is parallel to the pivot 15a. Some of the cutting discs 25 are placed on the shaft 24 above the block 27 and others are placed below the block. The arrangement is such that the pivot 28a is spaced from the upper end of the shaft 24 by about onethird of the length of the shaft. The cutters 236 and 23o are similar to the cutter 23a except that their cutting discs 25 are so divided by their blocks 27 that the upper ends and the lower ends of the three cutters 23a, 236, 230 are on the same level, notwithstanding the dierence in the level of the lower ends of the arms 17 a, 176, 17 c which, in the form shown, results from the difference in the level of the pivots 15a, 156, 150.

The cutting discs 25 are provided with cutting prongs 29 which project outwardly in planes perpendicular to the axisof the cutter sha-ft. In addition to the cutting discs 25 each cut-ter is provided with two cutting discs These discs are mounted, one near each end of the cutter shaft. Each of them is provided with inclined cutting prongs 31 which extend beyond the end of the cutter shaft.

Flat springs 33a, 336, 33e are secured to the arms 17 a, 17 6, 170. Each of these springs has an in-turned lower end 34 which presses against one of the blocks 27 below its pivot, and thus normally positions the cutter shaft 24 which extends through this block parallel to the arm on which it is mounted, as shown in Fig. 11.

A plunger 40 in the cylindrical chamber l12 provides means for swinging the three arms 17a, 176, 170 outwardly from the axis of the under-reamer. For this purpose push rods 41a, 416, 41C, extending through bores in the central port-ion 13 of the body, provide means for transmitting downward movement of the plunger 40 to the inner ends of the short arms 18a, 186, 180 of the three bell crank levers. To provide for the difference in the level of the pivots 15a, 156, 150 the push rods are made of progressively increasing lengt-h, the rod 410 being the longest.

The plunger 40 may be forced down by water forced into the chamber 12 through a central opening 42 in the upper end of the body. In order to provide for indicating the extent to which the arms 17 ai, 176, 17o have been swung out a variable leakage opening is provided. The variable leakage opening comprises the space between the walls of a central hole 43 in the plunger 40 and the outer wall of a cone 44 fixed on the closure 13. The water which passes through this variable leakage opening flows out of the lower portion of the chamber 12 through lat eral passages 45 in the cone 44, and a central hole 46 in the closure 13. A small axial passage 47 through the cone 44 permits some leakage of water through the plunger 40 and the chamber 12 even when the variable leakage opening is closed. It is apparent that the cross section of the variab-le leakage opening between the hole 43 and the cone 44 will progressively decrease as the plunger 40 is forced downward, swinging the arms 17a, 176, 17C outward.

The under-reamer is secured to the lower end of a hollow sectional drill rod 50 by screwing a threaded projection 51 at the upper end of the body 11 into the lower end of the lowest section of the drill rod. The upper end of the drill rod 5() is secured to the lower end of a grief stem 52 which is suspended through a water swivel 53 from the piston rod 54 of a hydraulic lift 55. rlhe upper end of the cylinder 56 of the lift is secured to the traveling block 57 of the drawout works of an ordinary oil-well derrick. The under-reainer may be rotated through the drill rod 50 by a rotary head 6() cooperating with the grief stem 52 in the ordinary Inanner. Water may be forced into the upper end of the under-reamer through the drill rod by a force pump 61 connected by a pipe 62 with the intake opening of the water swivel 53. A pressure gage 63 is mounted on the pump 61 or connected to the pipe 62, as shown.

The cylinder 56 of the hydraulic lift 55 is connected by a pipe 64 with a three-way valve 65 of usual construction and adapted to place the pipe 64 in communication, either with an outlet opening, or with the discharge of a force pump 66.

The use and operation of the under-reaming apparatus which has been described is as follows The under-reamer 10 and the sectional drill rod 50 are lowered into a well in the ordinary manner. Enough rod sections are attached to bring the under-reamer to the point in the well at which it is desired to form an enlarged cavity. The upper end of the drill rod 50 is then secured to the grief stem 52 which is supported by the means already described. During the lowering of the under-reamer, the arms 17a, `17 Z9, 17o hang down vertically, and the cutters 23a, 236, 230 are held parallel to the arms, with their upper cutting discs in the recesses in the arms, by the force of the springs 33a, 33t, 330. In consequence, no part ofthe under-reamer projects beyond the periph-ery of the cylindrical body to interfere with the lowering. Y

After the under-reamer has been lowered to the proper position, it is rotated by means of the rotary head 50 and water is forced into the upper part of the chamber l2 by means of the force pump 61. The pressure thus applied to the upper side of the plunger 40 urges the arms 17a, 176, 17o outwardly, bringing the cutters 23a, 235, 230 against the side walls of the well. Owing to the pivoting of the cutters, the outward pressure applied to them holds them approximately vertical against the walls of the well, so that as the under-reamer rotates they form an approximately cylindrical enlargement in the well. Owing to the effect of centrifugal force on the cutters, however, the cavity formed is slightly tapered, being largest at its upper end. The cutting action of the cutting discs 25 may be increased by moving the under-reamer slightly up and down during the cutting by manipulation of the three-way valve 65. As the cutting proceeds, the under-reamer is fed gradually downward by moving the three-way valve 65 so as to permit water to escape slowly from lfhe cylinder 56 of the hydraulic Y*lift 55. Such endwise movements of the under-ream er are greatly facilitated by the fact that the end cutting discs 30 have prongs projecting beyond the ends of the cutter shafts.

` As the wall of the well is cut away, the arms 17 a, 17?), 17 c swing outwardly more and'more and the plunger 30 moves down further. This results in a gradual closing of the variable leakage opening between the hole 43 and the cone 44. As this opening is decreased in size so that the flow of water through the chamber l2 is diminished, a rise in pressure is indicated on the gage 63. It follows that if the pump 61 is operated at a constant speed the exact diameter of the cavity may be ascertained at any moment during the under-reaming by reading` the gage 63. The may be calibrated so as to indicate the diameter of the cavity directly, or the diameter of the cavity may be calculated from a knowledge of the proportions of tl e bell crank levers and the taper of the cone 44;.

When a very large cavity is desired, the under-reamer may be moved downward by permitting the escape of water from the cylinder of the hydaulic lift whenever the arms 17a, 172'), 170 have swung out so far that they are likely to hit the upper edge of the cavity formed by the cutters. ln this way it is possible to form a stepped cavity whose bottom is of large diameter, as shown in Fig. 1.

During the cutting, the three cutters are always at substantially the same level, while the portions of the cutters which contain no cutting discs are each at a different level so that the partI of the wall not reached by the discs of one cutter is attacked by the discs of the other two.

rlhe provision of three cutters forced outwardly at equal angles from each other gives the under-reamer what may be termed a three-point support so that all side strain on the drill rod is avoided.

As the three cutters are forced out by a single plunger, ne one of them can be forced out more than the others. Consequently, the cutters will pass over a wider longitudinal fissure in the wall of the well without being caught in it than they would if they were forced out independently.

If any one of the cutters is suddenly forced inwardly by striking' a` hard obstruction, the

plunger l0 is moved upwardly in the chamber l2 so that no part of the mechanism is broken. Such upward yielding of theplunger 40 is made possible by the continuous leakage through the plunger which is'provided by means of the openings hereinbefore described.

Vihen a cavity of the desired size has been formed the pump 6l is stopped. The waterV remaining inv the' drill rod 50 flows out through the hole i8 in the plunger and the openings 45, or thrcugh the passage 47. In

this way the upper side of the plunger 4:0.k

is relieved of all hydrostatic pressure so that the plunger isV moved upward by the weight of the long arms 17a, 175, 17o of the bell crank levers. These arms, therefore, swing down into vertical position, drawing the cutters away from the wall of the cavity. Y The springs 33a, 33t), 33e swing the cutter shafts into vertical position so that no part of the under-reamer.projects beyond the periphery of its body and the under-reamer may easily be withdrawn from the well.

For the purpose of illustration, I have described a practical under-reaming apparatus embodying my invention. I wish it clearly understood, however, that my invention is by no means limited `to the particular form and arrangement of the parts of the apparatus described, except in so far as is specified in the claims which follow. Y

`What is claimed is:

l. An under-reamer, comprising a body containing a chamber, a plunger in said chamber, said parte being formed and arranged to provide a leakage opening between the portions of the chamber at opposite sides of the plunger and to decrease the cross-section of said opening progressively in accordance with the longitudinal movement of the plunger in the chamber in one direction, a cutter, 

